function json_encode(mixed_val) {
  //       discuss at: http://phpjs.org/functions/json_encode/
  //      original by: Public Domain (http://www.json.org/json2.js)
  // reimplemented by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  //      improved by: Michael White
  //         input by: felix
  //      bugfixed by: Brett Zamir (http://brett-zamir.me)
  //        example 1: json_encode('Kevin');
  //        returns 1: '"Kevin"'

  /*
    http://www.JSON.org/json2.js
    2008-11-19
    Public Domain.
    NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
    See http://www.JSON.org/js.html
  */
  var retVal, json = this.window.JSON;
  try {
    if (typeof json === 'object' && typeof json.stringify === 'function') {
      // Errors will not be caught here if our own equivalent to resource
      retVal = json.stringify(mixed_val);
      //  (an instance of PHPJS_Resource) is used
      if (retVal === undefined) {
        throw new SyntaxError('json_encode');
      }
      return retVal;
    }

    var value = mixed_val;

    var quote = function (string) {
      var escapable =
        /[\\\"\u0000-\u001f\u007f-\u009f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
      var meta = {
        // table of character substitutions
        '\b': '\\b',
        '\t': '\\t',
        '\n': '\\n',
        '\f': '\\f',
        '\r': '\\r',
        '"': '\\"',
        '\\': '\\\\'
      };

      escapable.lastIndex = 0;
      return escapable.test(string) ? '"' + string.replace(escapable, function (a) {
        var c = meta[a];
        return typeof c === 'string' ? c : '\\u' + ('0000' + a.charCodeAt(0)
          .toString(16))
          .slice(-4);
      }) + '"' : '"' + string + '"';
    };

    var str = function (key, holder) {
      var gap = '';
      var indent = '    ';
      // The loop counter.
      var i = 0;
      // The member key.
      var k = '';
      // The member value.
      var v = '';
      var length = 0;
      var mind = gap;
      var partial = [];
      var value = holder[key];

      // If the value has a toJSON method, call it to obtain a replacement value.
      if (value && typeof value === 'object' && typeof value.toJSON === 'function') {
        value = value.toJSON(key);
      }

      // What happens next depends on the value's type.
      switch (typeof value) {
      case 'string':
        return quote(value);

      case 'number':
        // JSON numbers must be finite. Encode non-finite numbers as null.
        return isFinite(value) ? String(value) : 'null';

      case 'boolean':
      case 'null':
        // If the value is a boolean or null, convert it to a string. Note:
        // typeof null does not produce 'null'. The case is included here in
        // the remote chance that this gets fixed someday.
        return String(value);

      case 'object':
        // If the type is 'object', we might be dealing with an object or an array or
        // null.
        // Due to a specification blunder in ECMAScript, typeof null is 'object',
        // so watch out for that case.
        if (!value) {
          return 'null';
        }
        if ((this.PHPJS_Resource && value instanceof this.PHPJS_Resource) || (window.PHPJS_Resource &&
          value instanceof window.PHPJS_Resource)) {
          throw new SyntaxError('json_encode');
        }

        // Make an array to hold the partial results of stringifying this object value.
        gap += indent;
        partial = [];

        // Is the value an array?
        if (Object.prototype.toString.apply(value) === '[object Array]') {
          // The value is an array. Stringify every element. Use null as a placeholder
          // for non-JSON values.
          length = value.length;
          for (i = 0; i < length; i += 1) {
            partial[i] = str(i, value) || 'null';
          }

          // Join all of the elements together, separated with commas, and wrap them in
          // brackets.
          v = partial.length === 0 ? '[]' : gap ? '[\n' + gap + partial.join(',\n' + gap) + '\n' + mind +
            ']' : '[' + partial.join(',') + ']';
          gap = mind;
          return v;
        }

        // Iterate through all of the keys in the object.
        for (k in value) {
          if (Object.hasOwnProperty.call(value, k)) {
            v = str(k, value);
            if (v) {
              partial.push(quote(k) + (gap ? ': ' : ':') + v);
            }
          }
        }

        // Join all of the member texts together, separated with commas,
        // and wrap them in braces.
        v = partial.length === 0 ? '{}' : gap ? '{\n' + gap + partial.join(',\n' + gap) + '\n' + mind + '}' :
          '{' + partial.join(',') + '}';
        gap = mind;
        return v;
      case 'undefined':
        // Fall-through
      case 'function':
        // Fall-through
      default:
        throw new SyntaxError('json_encode');
      }
    };

    // Make a fake root object containing our value under the key of ''.
    // Return the result of stringifying the value.
    return str('', {
      '': value
    });

  } catch (err) {
    // Todo: ensure error handling above throws a SyntaxError in all cases where it could
    // (i.e., when the JSON global is not available and there is an error)
    if (!(err instanceof SyntaxError)) {
      throw new Error('Unexpected error type in json_encode()');
    }
    this.php_js = this.php_js || {};
    // usable by json_last_error()
    this.php_js.last_error_json = 4;
    return null;
  }
}